1. Field of the Invention
This invention relates to a printing press, preferably a flexographic printing press, comprising at least one printing stand, in which an impression cylinder, two printing cylinders, which are movable into engagement with the impression cylinder, and inking rollers associated with said plate cylinders, are rotatably mounted, and a main drive, which is operatively connected to the impression cylinder, wherein the impression cylinder, the plate cylinders and the inking rollers comprise stub shafts, to which gears are secured, which are adapted to be in mesh for synchronous rotation during a printing operation.
2. Description of the Prior Art
Printing presses of that kind are known in various embodiments. For a movement to impression throw on and impression throw off positions and for a performance of large strokes for a change of the plate cylinder the plate cylinders are rotatably mounted in carriages, which are slidably mounted in the printing stand, and the inking rollers of the inking mechanisms are also rotatably mounted in carriages, which are guided on the plate cylinder carriages and are displaceable parallel to themselves.
A printing press of that kind can be set up for a given printing job in that the prepared plate cylinder intended to be used for that job or--for multicolor printing--the plate cylinders for printing in usually four or six different colors is or are installed. The change-over for a different printing job will involve a considerable down-time, which gives rise to high costs particularly in heavy-duty printing presses owing to the loss of production.
From Published German Application 34 32 572 it is known in a printing press to accelerate the impression cylinder, the plate cylinder and the inking roller by servomotors to a synchronous velocity, which is maintained by the servomotors during the printing operation.